The present invention relates to a vacuum pump as defined in the preamble of claim 1, designed to cooperate with a dust filter and a muffler according to the invention, which is further described below.
More specifically, the subject invention relates to an ejector type vacuum pump, comprising a rotationally symmetric ejector body that is housed to be surrounded by a vacuum chamber that extends axially to open through the house wall. A dust filter runs concentric about the ejector body, and has a tube shaped, porous filter body that is circumferentially supported in a frame such that the filter body and the frame together form a self-containing, rotationally symmetric unit that runs substantially about the total length of the ejector body. A muffler comprising a rotationally symmetric body has an inner end that is shaped to be sealingly seated in the mouth of the vacuum chamber. The inner section of the muffler is dimensioned to receive and enclose the nozzle end of the ejector body, and tapers towards the mouth of the muffler. The muffler is inserted in the mouth of the vacuum chamber and engages the dust filter for axial fixation of the filter in the vacuum chamber.
The object of the invention is to provide a vacuum pump of non-complex structure, and which by simplified structural measures may be incorporated in systems or assemblies where vacuum or negative pressure is desired for running a process.
Specifically, the vacuum pump of to the invention is designed to meet the object of facilitating assembly and disassembly in maintenance, when cleaning the dust filter or ejector, e.g. In industrial or otherwise polluted environments, service interrupts often is considered to be a technical and economic problem.
The object of invention is met in a vacuum pump as defined in the characterizing part of claim 1. The filter of claim 2 and muffler of claim 5 are separate elements of the invention, the common features of which is the structural adaptation to the rotationally symmetric ejector body, possibly of a multi stage configuration.
Briefly, the invention suggests a rotationally symmetric ejector body with one or several nozzles axially aligned and connected in series, and valve elements that are accommodated in the ejector body. The ejector is received in a vacuum chamber, formed in a house and opening axially in the house wall. The vacuum chamber is connected to a system, operated by negative pressure, and a compressed air supply is connected to the ejector so as to generate a negative pressure in the vacuum chamber through the ejector effect, as is known per se.
A separate attachable unit having a vacuum chamber and inlet for supply of compressed air, feeding the ejector, may form the vacuum pump house mentioned herein. Alternatively, the house is a vacuum chamber formed in the structure material of a system assembly, operated by negative pressure. The rotationally symmetric configuration of the ejector body allows a vacuum chamber to be formed in the structure material through boring and internal milling, so that a chamber of circular section is provided.
The vacuum chamber opens in a wall of the house or the structure material. The mouth of the vacuum chamber receives the circular sectioned muffler body, which occupies the annular space between the wall of the vacuum chamber and the nozzle end of the ejector body.
A dust filter is axially secured inwardly of the muffler. The filter runs concentric about the ejector body, substantially the whole length about the ejector body so that the forward end of the filter abuts the inner end of the muffler. The dust filter is a tube formed filter body of porous material. In the shown embodiment, the filter body is circumferentially enclosed by a frame having a perforated cylinder wall. Assembled, the filter and frame form a rotationally symmetric, self-containing unit that is manually attachable and detachable from the ejector body as the muffler is removed from the mouth of the vacuum chamber.